What effect humidity has on the hair during setting?

Humidity can significantly affect hair during setting by causing it to absorb moisture from the air, leading to frizz and loss of defined styles. High humidity can make hair swell, disrupting the shape of curls or straightened strands and resulting in a less polished appearance. Conversely, low humidity can lead to dryness, making hair brittle and more prone to breakage. Overall, maintaining the desired style becomes challenging in varying humidity levels.